In readily available prior art devices, imaging of penetrating radiation (X-rays, gamma radiation, and the like) is accomplished by converting the invisible input radiation into a visible image. Earliest methods and presently used methods include photographic film and fluorescent screens. These types use a finely granular sensitive material held in an organic binder and spread in a thin, uniform coat approximately 0.005 inches thick on a light cardboard or plastic film base. This choice of coating thickness is a compromise between resolution and capture efficiency of the imaging layer for the penetrating radiation. The capture and conversion of high percentages of a penetrating radiation require very thick converting layers, but "scatter" of the image in the thicker sensing material layers results in lower resolutions. Therefore, a useful rule relating to resolution in terms of television scan lines per inch is equal to the imaging layer's thickness. As a result, image resolution in these devices is always lower than desireable. The percentage of input radiation actually captured and contributing to the image is always lower than desireable and the efficiency is usually well below 1 percent in the ranges of most imaging devices. Therefore, over 99 percent of lost input radiation penetrating the imaging layer must be compensated by increasing the input radiation levels to overcome this lack of capture efficiency. This problem has been recognized for many years and the usual approach to combat this is to accept the uniformly thin, homogenous film conversion and try to improve the light output gain by methods, devices, and systems for improving output light gain after conversion. It has been thought impossible to capture and utilize higher percentages of penetrating radiation inputs without loss of resolution beyond acceptable limits by requiring excessive thickness in the conversion layer due to "scatter". Applicant in U.S. Pat. No. 4,096,381 has pointed out a way of utilizing large thicknesses in the conversion layer and still avoid "scatter". Even in light of applicant's patent, there is a need for even greater output efficiencies than produced by the device of applicants' patent.
Therefore, it is an object of this invention to provide a device and means which incorporate elementary conversion to provide solutions to the problem of making converters for penetrating radiation so as to provide means for a pre-established, high capture efficiency and pre-establish high resolution simultaneously and independently.
A further object of this invention is to provide a device and means for utilizing the elementary conversion device in such a manner as to produce an image of output penetrating radiation, optimized for a selected capture efficiency for the input radiation to be imaged, and means by which the image converter may be optimized to produce a desired high resolution.
Still another object of this invention is to provide a scintillating device in which image resolution and converter thickness are independently selectable as required to meet capture efficiency goals.
A still further object of this invention is to provide a scintillator device which is of a construction that allows a non-homogenous optically anisotropic imaging converter to be assembled and be substantially free of internal light scattering which destroys the image resolution when thick layers of scintillator material is used as employed in many other conventional converter devices.
Yet another object of this invention is to provide a converter that utilizes a fiber optic core which is made of scintillating material that is clad with a reflecting layer and a third layer of light absorbing material and finally a mirror surface on one end of the optical fiber to reflect light toward the other end of the fiber.
Other objects and advantages of this invention will be obvious to those skilled in this art.